class_docstr: A LangChain CallbackHandler that records callbacks for offline playback.
code: def on_tool_start(self, *args: Any, **kwargs: Any) -> None:
      self._append_record(CallbackType.ON_TOOL_START, args, kwargs)
  
imports: from __future__ import annotations
  import math
  import pickle
  import time
  from typing import Any, TypedDict
  from langchain.callbacks.base import BaseCallbackHandler
label_desc: Use image node_id 8 for calling the CapturingCallbackHandler obj's underlying member method code with example usage: obj.on_tool_start() without return types